Throttle valve opening detecting apparatus for a vehicle engine

Abstract

A throttle valve opening detecting apparatus of an automatic transmission for detecting an angular position or opening of a throttle valve for controlling the amount of air-fuel mixture reaching cylinders of a vehicle engine that includes a throttle valve position sensor for providing an output proportional to an angular position or opening of the throttle valve. A memory device memorizes a minimum value of the output to set a reference output for a closed position of the throttle valve. A renewing device decreasingly renews the reference output when the throttle valve position sensor provides an output smaller than the reference output set in the reference output. The renewing device increasingly renews the reference output when the throttle valve position sensor provides an output larger than the reference output and smaller than a preset reference output for a predetermined or preselected period of time.

What is claimed is: 
     
       1. A throttle valve opening detecting apparatus for a vehicle engine connected with an automatic transmission comprising: a throttle valve disposed in an intake manifold of a vehicle engine for controlling the amount of intake air reaching cylinders of said vehicle engine;   throttle valve opening sensor for providing an output proportional to an opening of said throttle valve;   reference output setting means for setting therein an output as a reference output representative of a closed position of said valve;   control means for receiving said output from said throttle valve opening sensor to decreasingly renew said reference output in said reference output setting means when the smallest output from said throttle valve opening sensor is smaller than said reference output or increasingly renew said reference output in said reference output setting means when said output from said throttle valve opening sensor is continuously larger than said reference output for a predetermined period of time while it is smaller than a predetermined output; and   operating means for obtaining a ratio of opening of said throttle valve to be controlled based on a current output from said throttle valve opening sensor and said renewed reference output to provide a control signal representative of said opening ratio.   
     
     
       2. A throttle valve opening detecting apparatus as defined in claim 1, wherein said opening ratio of said throttle valve is obtained as a ratio of the difference between a preset output representative of the maximum opening of said throttle valve and said renewed reference output to the difference between a current output from said throttle valve opening sensor and said renewed reference output. 
     
     
       3. A throttle valve opening detecting apparatus as defined in claim 1, wherein said opening ratio of said throttle valve is obtained as a ratio of the difference between preset outputs representative of the maximum and the minimum opening of said throttle valve to the difference between a current output from said throttle valve opening sensor and said renewed reference output. 
     
     
       4. A throttle valve opening detecting apparatus as defined in claim 1, wherein, upon decreasingly renewing said reference output, an output from said throttle valve opening sensor smaller than said reference output is set as a renewed reference output in said reference output setting means. 
     
     
       5. A throttle valve opening detecting apparatus as defined in claim 1, wherein said preset reference output is set to an output for said throttle valve opened to a ratio of opening between 1/25 and 1/8. 
     
     
       6. A throttle valve opening detecting apparatus as defined in claim 5, wherein said reference output renewing means increasingly renews said reference output when an output from said throttle valve opening sensor is continuously kept unchanged for a predetermined period of time. 
     
     
       7. A throttle valve opening detecting apparatus as defined in claim 6, wherein said reference output increasingly renewing means renews said reference output when said unchangeable output continually appears for predetermined times. 
     
     
       8. A throttle valve opening detecting apparatus as defined in claim 1, wherein said reference output renewing means increasingly renews said reference output to an output increased by a predetermined output from said reference output. 
     
     
       9. A throttle valve opening detecting apparatus as defined in claim 1, wherein said vehicle engine is equipped with an automatic transmission with a lockup torque converter, lockup control and gear ratio control of said automatic transmission being performed based on an automatic vehicle speed control schedule drawn from a plurality of preset automatic vehicle speed control schedules depending upon said throttle valve opening ratio obtained by said operating means and a vehicle speed. 
     
     
       10. A throttle valve opening detecting apparatus as defined in claim 9, wherein, when said throttle valve opening sensor provides no output, said reference output setting means set therein a value corresponding to an output to be ordinarily provided by said throttle valve opening sensor when said throttle valve is opened half, thereby unlocking said lockup clutch. 
     
     
       11. A throttle valve opening detecting apparatus as defined in claim 1, wherein said throttle valve opening sensor comprises a variable resistance with a movable contact in cooperation with said throttle valve, a power source for applying a constant voltage to a fixed resistance of said variable resistance, and a potential detector for detecting a potential of said movable member. 
     
     
       12. A throttle valve opening detecting apparatus as defined in claim 1, wherein said reference output setting means is interrupted to set a reference output when the temperature of an engine coolant is lower than 50° C. 
     
     
       13. A throttle valve opening detecting apparatus for a vehicle engine connected with an automatic transmission comprising: a throttle valve disposed in an intake manifold of a vehicle engine for controlling the amount of intake air reaching cylinders of said vehicle engine;   throttle valve opening sensor for providing an output proportional to an opening of said throttle valve;   reference output setting means for setting therein an output as a reference output representative of a closed position of said valve;   control means for receiving said output from said throttle valve opening sensor to decreasingly renew said reference output in said reference output setting means when the smallest output from said throttle valve opening sensor is smaller than said reference output or increasingly renew said reference output in said reference output setting means when said output from said throttle valve opening sensor is continuously larger than said reference output for a predetermined period of time while it is smaller than a predetermined output; and   means for judging whether said throttle valve is in an idle position by comparing said output from said throttle valve opening sensor with said reference output set in reference output setting means.   
     
     
       14. A throttle valve opening detecting apparatus as defined in claim 13, wherein, upon decreasingly renewing said reference output, said output lower than said reference output is set as a renewed reference output in said reference output setting means. 
     
     
       15. A throttle valve opening detecting apparatus as defined in claim 13, wherein said preset reference output is set to an output for said throttle valve opened to a ratio of opening between 1/25 and 1/8. 
     
     
       16. A throttle valve opening detecting apparatus as defined in claim 15, wherein said reference output renewing means increasingly renews said reference output when an output from said throttle valve opening sensor is continuously kept unchanged for a predetermined period of time. 
     
     
       17. A throttle valve opening detecting apparatus as defined in claim 16, wherein said reference output renewing means renews increasingly said reference output when said unchangeable output continually appears for predetermined times. 
     
     
       18. A throttle valve opening detecting apparatus as defined in claim 16, wherein, upon increasingly renewing said reference output, an output from said throttle valve opening sensor is continuously kept unchanged as a renewed reference output in said reference output setting means. 
     
     
       19. A throttle valve opening detecting apparatus as defined in claim 18, wherein said vehicle engine is equipped with an automatic transmission with a lockup torque converter, said lockup torque converter being unlocked always when said throttle valve is judged to be closed.